Fix a command error in nodes.rst
Fix a command error in nodes.rst

Change-Id: I0cc48b0cc246c49f8870a35425e73fce53939aa2
Signed-off-by: Alex Yang <8f79ad8057698d8997f8703a63d91b00d6ba955c@zte.com.cn>

stackforge/senlin,openstack/senlin,stackforge/senlin,openstack/senlin,openstack/senlin